Explosively actuated stud driving apparatus



Dec. 3, 1963 Filed Jan. 30, 1962 INVENTOR ATTOR United States Patent Ofidce '3 ,l HA8? Patented Dec. 3, 1963 3,112,437 EXPLGSIVELY ACTUATED STUD DRWIN G APPARATUS Martin Hilti, Vaduz, Liechtenstein, assignor to Anstalt fiir lt'Iontage-Technik, Vaduz, Liechtenstein Filed Jan. 30, 1962, Ser. No. 169,916 Claims priority, application Germany Feb. 2, 1%1 7 Claims. (Cl. 1-445) This invention relates to stud-driving apparatus of the class wherein an explosive charge is used to provide at least part of the force for driving the stud. More in particular, this invention relates to means for properly disposing of the combustion products of the explosive charge.

A tool of the type for which the present invention is especially adapted is shown in copending application Serial No. 795,819, filed February 26, 1959 by the present applicant. Such a tool comprises a tubular guide member within which is slidably mounted a hammer member for applying the required driving force to thestud. Above the hammer member is a piston member the lower end of which carries a cartridge and the upper end of which is adapted to be struck, as by a hand-held driver, in order to fire the cartridge by impacting its base against the hammer member. The tubular guide also is provided, at its lower end, with radially extending passages through which the combustion gases from the cartridge can pass into a sealed annular expansion chamber located between the outer wall of the tubular guide and the inner wall of a surrounding jacket which serves as the handle for the tool.

Experience with such tools has shown that combustion products tend to accumulate along the walls of the gas expmsion chamber, particularly in the region directly opposite the exit openings of the passages, and thus it is necessary periodically to disassemble the tool to clean out the residues. In one embodiment of the present invention, to be described hereinbelow in more detail, this periodic disassembly and cleaning is substantially minimized by providing additional passages communicating between the upper end of the expansion chamber and the upper interior of the tubular guide. With this arrangement, the combustion products which pass into the lower end of the chamber can escape into the upper interior of the tubular guidefrom which they can readily be removed without major disassembly of the tool.

Accordingly, it is an object of this invention to provide improved stud-driving apparatus. It is a further object of this invention to provide an explosively-operated studdriv-ing tool having means for directing the combustion products into a region of the tool from which they can readily be removed without major disassembly. Other objects, aspects and advantages of the invention will in part be pointed out in, and in part apparent from, the following description considered together with the accompanying drawing which is a vertical section of a preferrcd embodiment of the tool.

Referring now to the drawing, the tool includes a tubular guide 1 within which is slidably mounted a piston member 2 having at its lower end a head 3 closely fitted to the tubular guide to seal the explosive gases. Below the piston head 3 is a slidable hammer member 13 which also is sealiugly fitted to the tubular guide. As in the tool described in the above-mentioned copending application, the upper surface of the hammer member is provided with a firing pin 15 adapted to engage the base of a cartridge positioned in a recess in the piston head 3. The reduceddi-ameter portion 14 of the hammer member 13 is arranged to engage the head of the stud, and the shank of the stud is guided in the usual way by means of a metal washer held in place by a magnet. When the upper end second set of passages 6 extending obliquely,

of the piston member 2 is struck, the impact between the cartridge and the firing pin 15 ignites the cartridge and the propellant gases drive the hammer member downward to force the stud into the workpiece.

At the lower end of the tubular guide 1 are two passages 22 which extend obliquely, upwardly and outwardly, to connect the interior of the tubular guide to an annular chamber 23 formed by an outer jacket 4 with a rubber handle 24. When the hammer member 13 has been driven by the cartridge explosion down below the entrance to these passages, the combustion gases stream through the passages and into the expansion chamber 23. The oblique angle of the passages avoids concentrated build-up of combustion products on the chamber wall.

At the upper end of the expansion chamber 23 is a upwardly and inwardly, to the upper interior of the tubular guide 1, i.e. above the piston head 3. With this arrangement, a large portion of the combustion products pass from chamber 23 into the interior of the tubular guide, and thus escape to the outside through the usual gaps between the tubular guide and an upper end member 5. The oblique angle of the passages 6 avoids concentrated build-up of combustion products on the piston member 2.

Any residues which accumulate on the upper inner wall of the tubular guide 1 are automatically scraped 01f by the piston head 3 when the piston is moved back to its uppermost position. Such accumulations of combustion products can readily be cleaned off when the piston is removed from the tool. To provide good scraping action, the outer edge of the upper surface 7 of the piston head 3 preferably is made sharp in order to cut through any residue accumulated on the inner wall of the tubular guide.

Removal of the piston from the tool can be facilitated by using a conventional bayonettype closure to secure upper end member 5 to tubular guide -1. Such an arrangement is described in the copending application previously referred to, and thus is not shown in detail herein. However, to briefly outline the arrangement as used with the present invention, the lower portion of the upper end member 5 and the upper neck portion of the tubular guide 1 have two partially circumferential overlapping flanges forming the bayonet-type closure. For removal of the piston 2, the member 5 is rotated to a, position where its flanges no longer overlap the flanges of the tubular guide 1, and the end members is simply pulled off the tubular guide, thus permitting removal of the piston. For further disassembly of the tool, the outer jacket 4 and the rubber handle 24 can then be removed by sliding them off the tubular guide 1. The exterior surface of the tubular guide 1 and the interior surface of the outer jacket 4, which in the assembled position form the expansion chamber 23, are thus exposed and can be cleaned whenever necessary.

Although a preferred embodiment of this invention has been set forth in detail, it is desired to emphasize that this is not intended to be exhaustive or necessarily limitative; on the contrary, the showing herein is for the purpose of illustrating the invention and thus to enable others skilled in the art to adapt the invention in such ways as meet the requirements of particular applications, it being understood that various modifications may be made without departing from the scope of the invention as limited by the prior art.

I claim:

1. Stud-driving apparatus comprising guide means defining an enclosed slideway, a hammer member slidably mounted in said guide means for driving a stud into a workpiece, a piston member slidably mounted in said guide means above said hammer member, one of said members having means to fire a cartridge carried by the other member for propelling said hammer member against the stud, means connected to said guide means and forming a gas expansion chamber, first passage means connecting the lower interior of said sli-deway to said chamber to direct the cartridge combustion gases into said chamber, and second passage means connecting said chamber and the upper interior of said slideway to permit combustion gases to escape from said chamber to reenter the interior of the slideway.

2. Stud-driving apparatus comprising a tubular guide, a hammer member slidably mounted in said guide for driving a stud into a workpiece, said hammer member forming a sealing fit with said guide, a piston member having a head slida'bly mounted in said guide above said hammer member and forming a sealing fit with said guide, one of said members having means to fire a cartridge carried by the other member, said guide having a gas expansion chamber therein, said guide having a first passage connecting said chamber to the lower interior of said guide to permit the explosive gases from said cartridge to enter said chamber, said guide having a second passage connecting said chamber to the upper interior of said guide to permit combustion gases to escape from said chamber and to reenter the interior of said guide above said piston member head.

3. Stud-driving apparatus comprising first means having a bore, a hammer member slidably mounted in said bore and adapted to engage a stud to apply driving force thereto, a piston member slidably mounted in said bore above said hammer member, one of said members having means to fire a cartridge carried by the other member to force said hammer member against the stud, second means surrounding said first means and spaced therefromto form a gas expansion chamber, said first means having a first passage extending between said chamber and the lower end of said bore to permit the discharge of combustion gases after said hammer member has passed the entrance to said first passage, said first means having a second passage extending between said chamber and the upper end of said bore to permit said combustion gases to escape out of said chamber.

4. Stud-driving apparatus comprising a tubular guide, a hammer member slidably mounted in said guide for driving a stud into a workpiece, said hammer member forming a sealing fit with said guide, a piston member having a head slidably mounted in said guide above said hammer member and forming a sealing fit with said guide, one of said members having means to fire a cartridge carried by the other member, said guide having a gas expansion chamber therein, said guide having a first passage connecting said chamber to the lower interior of said guide to permit the explosive gases from said cartridge to enter said chamber, said first passage extending at an oblique angle With respect to the longitudinal axis of said tubular guide, said guide having a second passage connecting said chamber to the upper interior of said guide to permit combustion gases to escape from said chamber and to reenter the interior of said guide above said piston member head.

5. Apparatus as claimed in claim 4, wherein said sec ond passage extends at an oblique angle with respect to the longitudinal axis of said tubular guide.

6. Stud-driving apparatus comprising first means having a bore, a hammer member slidably mounted in said bore and adapted to engage a stud to apply driving force thereto, a piston member slida-bly mounted in said bore above said hammer member, one of said members having means to fire a cartridge carried by the other member to force said hammer member against the stud, second means surrounding said first means and spaced therefrom to form a gas expansion chamber, said first means having a first passage extending between said chamber and the lower end of said bore to permit the discharge of combustion gases after said hammer member has passed the entrance to said first passage, said first means having a second passage extending between said chamber and the upper end of said bore to permit said combustion gases to escape out of said chamber and back to said bore above said piston member, the upper surface of said piston member having a sharp side edge to provide a scraping action for rernoving combustion products from the walls of said bore.

7. Stud-driving apparatus comprising tubular guide means having a central bore, a hammer member slidably mounted in said bore and adapted to engage a stud to apply driving force thereto, a piston member slidably mounted in said bore above said hammer member, one of said members having means to fire a cartridge carried by the other member to force said hammer member against the stud, jacket means surrounding said tubular guide means and spaced therefrom to form an annular gas expansion chamber, said tubular guide means having a first passage connecting the lower end of said bore to said expansion chamber to direct the combustion gases into said chamber after said hammer member has passed the entrance to said first passage during a stud driving operation, said first passage extending outwardly an-d upwardly at an oblique angle with respect to the longitudinal axis of said tubular guide means, said tubular guide means having a second passage connecting said chamber to the upper end of said bore to perrnitsaid combustion gases to escape out of said chamber and into said bore above said piston member, said second passage extending inwardly and upwardly at an oblique angle with respect to the longitudinal axis of said tubular guide means.

References Cited in the file of this patent UNITED STATES PATENTS 2,773,259 Broughton Dec. 11, 1956 FOREIGN PATENTS 1,221,131 France Jan. 11, 1960 

1. STUD-DRIVING APPARATUS COMPRISING GUIDE MEANS DEFINING AN ENCLOSED SLIDEWAY, A HAMMER MEMBER SLIDABLY MOUNTED IN SAID GUIDE MEANS FOR DRIVING A STUD INTO A WORKPIECE, A PISTON MEMBER SLIDABLY MOUNTED IN SAID GUIDE MEANS ABOVE SAID HAMMER MEMBER, ONE OF SAID MEMBERS HAVING MEANS TO FIRE A CARTRIDGE CARRIED BY THE OTHER MEMBER FOR PROPELLING SAID HAMMER MEMBER AGAINST THE STUD, MEANS CONNECTED TO SAID GUIDE MEANS AND FORMING A GAS EXPANSION CHAMBER, FIRST PASSAGE MEANS CONNECTING THE LOWER INTERIOR OF SAID SLIDEWAY TO SAID CHAMBER TO DIRECT THE CARTRIDGE COMBUSTION GASES INTO SAID CHAMBER, AND SECOND PASSAGE MEANS CONNECTING SAID CHAMBER AND THE UPPER INTERIOR OF SAID SLIDEWAY TO PERMIT COMBUSTION GASES TO ESCAPE FROM SAID CHAMBER TO REENTER THE INTERIOR OF THE SLIDEWAY. 